This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application for CATHODE RAY TUBE HAVING A TENSIONED MASK earlier filed in the Korean Industrial Property Office on 27 Mar. 2001 and there duly assigned Ser. No. 2001-15951.
1. Field of the Invention
The present invention relates to a cathode ray tube and, more particularly, to a cathode ray tube which has a color selection apparatus bearing a tension mask.
2. Description of the Related Art
A cathode ray tube, the most popular display device, has been developed in various formats while keeping pace with the times. Recently, a wide screen cathode ray tube has been the choice of electronic consumers.
In order to enlarge the screen size, the screen panel should be flat in consideration of the quality of the screen images displayed at the periphery of the screen.
As the panel becomes enlarged and flattened, a shadow mask for the color selection apparatus is also enlarged in size. In consideration of various difficulties related to the enlargement of the curved shadow mask such as a weak strength thereof, a new-modeled color selection apparatus has been now employed for use in the cathode ray tube.
Such a color selection apparatus has a structure where a mask with a plurality of beam-guide holes is not curved but flattened while bearing a predetermined tension. For instance, U.S. Pat. No. 5,111,107 by Kume et al. for Grid Apparatus for a Color Cathode Ray Tube which Eliminates Vibration of the Grids discloses a grid apparatus bearing such a structure.
The grid apparatus has a plurality of slender and long grid members fitted to a frame while being tensioned in the longitudinal direction (X-axis direction). The frame has a pair of support bars arranged parallel to each other, with a predetermined distance between them, and connected to the grid members, and elastic members attached to the ends of the support bars while being positioned between them.
The grid apparatus further has metallic members attached to the elastic members, and has a thermal expansion coefficient greater than that of the latter. The metallic members prevent the grid members from suffering thermal deformation during the heat treatment process.
Meanwhile, a plurality of phosphors are formed at the internal surface of the panel in the X-axis direction (in the direction of the short axis of the panel) while corresponding to the pattern of beam-guide holes formed by the grid members. A black matrix is formed between the neighboring phosphors.
However, in the above-structured cathode ray tube, when the plurality of phosphors are arranged in the above-described manner to form a phosphor screen, mis-landing of the electron beams is liable to occur at the periphery of the screen while causing deterioration in picture quality due to the color spots.
The electron beams should correctly land on the phosphors at the periphery of the screen under the influence of the vertical magnetic field component of the terrestrial magnetism. However, with the above structure, the electron beams move in the direction vertical to the X-axis direction (the direction of Y-axis), and land on the incorrect phosphors.
In order to solve such a problem, it has been suggested that the phosphors should be arranged in the direction of the long axis of the panel (or in the horizontal direction). For instance, such a cathode ray tube is disclosed in Korean Patent Publication No. 91-10602 by Yim et al. for Color Cathode Ray Tube, U.S. Pat. No. 5,099,169 by Vriens for Shadow Mask Color Display Tube, U.S. Pat. No. 5,170,102 by Sluyterman et al. for Picture Display Device, and U.S. Pat. No. 5,889,362 by Barten for Color Display Tube having a Reduced Deflection Defocusing. 
However, the above patents are only related to a cathode ray tube having no tension mask.
In order to prevent miss-landing of the electron beams with the cathode ray tube bearing a tension mask, various conditions, such as the arrangement pattern of phosphors, the tensioned state of the shadow mask and the shape of the panel, should be satisfied in an appropriate manner. In this way, the resulting flat cathode ray tube can have good picture quality.
It is an object of the present invention to provide a color correction apparatus for a cathode ray tube that prevents mis-landing of electron beams at the periphery of the display screen.
It is another object of the present invention to provide a cathode ray tube that prevents possible explosion with the enlarged flat panel.
It is still another object of the present invention to provide a cathode ray tube that has a reasonable weight even with the enlarged flat panel.
These and other objects may be achieved by a cathode ray tube with the following features.
According to one aspect of the present invention, a color selection apparatus for the cathode ray tube includes a mask having a short and a long axis, and a frame combined with the mask such that the mask is kept in a tensioned state. The mask is provided with a plurality of beam-guide holes. The mask is tensioned in the long axis direction while being supported by the frame.
The mask has a plurality of strips spaced apart from each other by a predetermined distance, and real bridges disposed between the neighboring strips while being spaced apart from each other by a predetermined distance. The beam-guide holes are formed with a plurality of slots longitudinally proceeding in the long axis direction while being partitioned by the real bridges.
Alternatively, the mask may have only a plurality of strips spaced apart from each other by a predetermined distance. In this structure, the beam-guide holes are formed with single slots longitudinally proceeding in the long axis direction while being disposed between the neighboring strips.
According to another aspect of the present invention, the cathode ray tube includes a panel with a substantially flat outer surface and an inner curved surface. The inner curved surface of the panel has a phosphor screen. A funnel is connected to the panel while externally mounting a deflection unit for deflecting electron beams. A neck is connected to the funnel while internally mounting an electron gun for emitting the electron beams. A color selection apparatus is internally fitted to the panel such that the electron beams land on correct phosphors of the phosphor screen. The panel has an effective screen with a short and a long axis. The panel has a first thickness Th at the ends of the effective screen in the long axis direction, and a second thickness Tv at the ends of the effective screen in the short axis direction. The second thickness Tv of the panel is established to be larger than the first thickness Th of the panel. The color selection apparatus has a mask with a short and a long axis while having a plurality of beam-guide holes, and a frame combined with the mask such that the mask is kept in a tensioned state. The mask is tensioned in the long axis direction while being supported by the frame.
The panel has a third thickness Tc at the center of the effective screen while satisfying the following condition: V/Hxe2x89xa71.1. where V(%) is (Tv/Tc)xc3x97100, and H(%) is (Th/Tc)xc3x97100.
According to still another aspect of the present invention, the cathode ray tube includes a panel with a substantially flat outer surface and an inner curved surface. The inner curved surface of the panel has a phosphor screen. A funnel is connected to the panel while externally mounting a deflection unit for deflecting electron beams. A neck is connected to the funnel while internally mounting an electron gun for emitting the electron beams. A color selection apparatus is internally fitted to the panel such that the electron beams land on correct phosphors of the phosphor screen. The phosphor screen is shaped with a short and a long axis, and the phosphors are longitudinally arranged on the phosphor screen in the long axis direction. The color selection apparatus has a mask with a plurality of beam-guide holes corresponding to the phosphors, and a frame combined with the mask such that the mask is kept tensioned in the long axis direction. The electron beams emitted from the electron gun are directed toward the phosphor screen in a line while being parallel to the short axis of the phosphor screen.